Bill Phillips' program Body for Life shoots for a 40/40/20 split and give the guideline that you should shoot for protein to look like the palm of your hand (minus the fingers) and the carbs should be about the size of your closed fist. So, if you had chicken and brown rice as a meal, the amount of chicken would be your palm (about the size of a breast, huh?) and the rice on your plate would be about the size of your closed fist.

Those are often pretty close to what you need to make it simple without measuring and counting calories. Not always perfect, but it is pretty close.